[PATCH v2] Check for existence of GNU-style strerror_r

[Ulf Hermann]

If we don't have it, we don't translate system error codes to strings in
dwfl_error.c.

Signed-off-by: Ulf Hermann <ulf.herm...@qt.io>
---
 ChangeLog            | 4 ++++
 configure.ac         | 2 ++
 libdwfl/ChangeLog    | 5 +++++
 libdwfl/dwfl_error.c | 4 ++++
 4 files changed, 15 insertions(+)

diff --git a/ChangeLog b/ChangeLog
index dd9b9ac..1acc8ba 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
 2017-02-22  Ulf Hermann  <ulf.herm...@qt.io>
 
+       * configure.ac: Check for strerror_r and its variants.
+
+2017-02-22  Ulf Hermann  <ulf.herm...@qt.io>
+
        * configure.ac: Add check for fputs_unlocked.
 
 2017-02-22  Ulf Hermann  <ulf.herm...@qt.io>
diff --git a/configure.ac b/configure.ac
index 8119e07..ce40539 100644
--- a/configure.ac
+++ b/configure.ac
@@ -309,6 +309,8 @@ AC_CHECK_DECLS([fputs_unlocked],[],[],
                [#define _GNU_SOURCE
                 #include <stdio.h>])
 
+AC_FUNC_STRERROR_R
+
 AC_CHECK_LIB([stdc++], [__cxa_demangle], [dnl
 AC_DEFINE([USE_DEMANGLE], [1], [Defined if demangling is enabled])])
 AM_CONDITIONAL(DEMANGLE, test "x$ac_cv_lib_stdcpp___cxa_demangle" = "xyes")
diff --git a/libdwfl/ChangeLog b/libdwfl/ChangeLog
index f5921dc..1a23136 100644
--- a/libdwfl/ChangeLog
+++ b/libdwfl/ChangeLog
@@ -1,5 +1,10 @@
 2017-02-22  Ulf Hermann  <ulf.herm...@qt.io>
 
+       * dwfl_error.c: If we don't have a strerror_r returning a char*,
+       output a less useful message in case of a system error.
+
+2017-02-22  Ulf Hermann  <ulf.herm...@qt.io>
+
        * dwfl_module_getsrc_file.c: Include system.h.
 
 2017-02-22  Ulf Hermann  <ulf.herm...@qt.io>
diff --git a/libdwfl/dwfl_error.c b/libdwfl/dwfl_error.c
index 7bcf61c..aba3cca 100644
--- a/libdwfl/dwfl_error.c
+++ b/libdwfl/dwfl_error.c
@@ -154,7 +154,11 @@ dwfl_errmsg (int error)
   switch (error &~ 0xffff)
     {
     case OTHER_ERROR (ERRNO):
+#ifdef STRERROR_R_CHAR_P
       return strerror_r (error & 0xffff, "bad", 0);
+#else
+      return "Unknown error. See errno";
+#endif
     case OTHER_ERROR (LIBELF):
       return elf_errmsg (error & 0xffff);
     case OTHER_ERROR (LIBDW):
-- 
2.1.4